Read the text and asnwer the following question!

    It happened on Sunday morning a few days ago. When I was about to have my routine cup of coffee along with a bagel, I realized that I did not have any bread at all. I have to admit that I am unable to enjoy coffee without some kind of baked goods.

    Then I decided to run out to buy something, but all the stores were closed, but one. That store did not have any fresh pastries, and I ended up buying four slices of wheat bread. I was frustrated for two reasons: firstly, I couldn’t enjoy drinking my coffee on Sunday morning; and secondly, the sales woman charged me $3.00 for four slices of bread!

    Next, I returned to the building where I live on the tenth floor, stepped into the elevator, pushed the button, and got out. When I reached my apartment and tried to unlock the door, I could not turn the key. I made a few attempts without success. I started banging on the door hoping to wake up my daughter. I was not successful at that either.

    I can’t explain how it crossed my mind to check the number of the apartment. The apartment number was correct, except for the first digit: the apartment was on the ninth floor, but the tenth. I was shocked to realize that I had been banging on somebody else’s door.

    I still muse over what might have happened if somebody had opened the door and what he or she would have said to me at 8:00 am on Sunday morning.

Why was the writer frustrated that morning?